ASME VIII 2-2025中的载荷工况
2025版AS ME有很多新变化，我们也在不断的学习总结，下面是AS ME VIII2-2025中的一段原话，我们翻译一下，然后重点说一下需要注意的地方。
5.1.3 LOADING CONDITIONS
5.1.3.1 Applicable Loads. All applicable applied loads on the component shall be considered when performing a design-by-a nalysis. Supplemental loads shall be considered in addition to the applied pressure in the form of applicable load cases. If the load case varies with time, a loading time history shall be developed to show the time variation of each specific load. The load case definition shall be included in the User’s Design Specification. An overview of the supplemen tal loads and loading conditions that shall be considered in the design are shown in Table 5.1. 5.1.3.2 Load Case Combinations. (a) Load case combinations shall be considered in the a nalysis. Typical load descriptions are provided in Table 5.2. Load case combinations for elastic an alysis, limit load a nalysis, and elastic–plastic an alysis are shown in Table 5.3, Table 5.4, and Table 5.5, respectively. Load case combinations for Protection Against Collapse from Buckling are shown in Table 5.15. Load case combinations for using the elastic stress an alysis method in the creep regime are shown in Table 5.16. The applicable load case combinations shall be considered in addition to any other combinations defined in the User’s Design Specification. (b) In evaluating load cases involving the pressure term, P, the effects of the pressure being equal to zero shall be considered. (c) The factors for wind loading, W, in Table 5.3, Table 5.4, Table 5.5, and Table 5.15 are based on ASCE/SEI 7 wind maps and probability of occurrence. If a different recognized standard for wind loading is used, the User’s Design Spec ification shall cite the Standard to be applied and provide suitable load factors if different from ASCE/SEI 7. (d) The factors for seis mic loading, E, in Table 5.3, Table 5.4, Table 5.5, and Table 5.15, are based on ASCE/SEI 7. If a different recognized standard for earthquake or snow loading is used, the User’s Design Specification shall cite the Stan dard to be applied and provide suitable load factors if different from ASCE/SEI 7. (e) The factors for snow loading, Ss, in Table 5.3, Table 5.4, Table 5.5, and Table 5.15, are based on ASCE/SEI 7. If a different recognized standard for snow loading is used, the User’s Design Specification shall cite the Standard to be ap plied and provide suitable load factors if different from ASCE/SEI 7. 5.1.3.3 Loads That Vary With Time. If any of the loads vary with time, a loading time history shall be developed to show the time variation of each specific load. The loading time history shall include all significant operating tempera tures, pressures, supplemental loads, and the corresponding cycles or time periods for all significant events that are ap plied to the component. The following shall be considered in developing the loading time history: (a) the number of cycles associated with each event during the operating life. These events shall include start-ups, normal operation, upset conditions, and shutdowns (b) the anticipated sequence of operation. When it is not possible or practical to develop a loading time history based on the actual sequence of operation, a loading time history may be used that bounds the actual operation. Otherwise, the cyclic evaluation shall account for all possible combinations of loadings. (c) applicable loadings such as pressure, temperature, and supplemental loads such as weight, support displacements, and nozzle reaction loadings. (d) the relative timing of the applied loadings during the time history
5.1.3 载荷工况
5.1.3.1 适用载荷
采用分析设计法时，应考虑构件承受的所有实际作用载荷。除压力载荷外，还应按适用载荷组合工况考虑附加载荷；若载荷随时间变化，应建立载荷时间历程，表征各项特定载荷随时间的变化规律。载荷工况定义应纳入用户设计说明书。设计中需考虑的附加载荷与载荷工况概览见表 5.1。
5.1.3.2 载荷工况组合
(a) 分析过程必须考虑载荷工况组合，典型载荷说明见表 5.2。弹性分析、极限载荷分析、弹塑性分析对应的载荷组合分别见表 5.3、表 5.4、表 5.5；屈曲垮塌防护载荷组合见表 5.15；蠕变范围内采用弹性应力分析法的载荷组合见表5.16。除用户设计说明书规定的其他组合外，仍应执行上述适用载荷组合。
(b) 校核含压力P的载荷工况时，必须考虑压力为零的极端工况效应。
(c) 表 5.3、5.4、5.5、5.15 中风载荷W系数，依据 ASCE/SEI 7 风压分布图及发生概率取值。若采用其他公认风荷载标准，应在用户设计说明书注明所用标准；与 ASCE/SEI 7 系数不同时，应提供适配载荷系数。
(d) 上述表格中地震载荷E系数依据 ASCE/SEI 7。若采用其他公认地震或雪荷载标准，应在用户设计说明书注明标准名称，并提供对应适配载荷系数。
(e) 上述表格中雪荷载Ss系数依据 ASCE/SEI 7。若采用其他公认雪荷载标准，应在用户设计说明书注明标准，并提供差异化适配载荷系数。
5.1.3.3 随时间变化的载荷
任意载荷随时间波动时，应编制载荷时间历程，列明构件所有关键工况对应的操作温度、压力、附加载荷，以及对应循环次数或持续时长。编制载荷时间历程应考虑：
(a) 设计寿命内各类工况的循环次数，包括开机、正常运行、异常工况、停机；
(b) 预期运行次序；无法按实际次序编制时，可采用包络实际工况的载荷时间历程；否则循环评定需涵盖所有可能载荷组合；
(c) 压力、温度及自重、支座沉降、管口反力等附加作用载荷；
(d) 时间历程中各类作用载荷的同步时序关系。
总结：我们做过很多的应力分析计算，结合新标准来看，还是要把载荷工况确定好，不能疏漏，当然也要看具体情况，设计者最起码要把该做的工况计算完成，但又不能过度的增加工况带来不必要的工作量。压力为零的工况，这个是当时我们考SAD作业答辩的时候，问如果压力为零或者很小时，那应力该怎么评定，还是二次应力吗？这个就不能盲目的按照标准规范来评定了，更多的是一次弯曲应力为主了，比如大型料仓在大端出现开裂的情况，如果还是按照二次应力去评定，那就容易出现问题，这个实际反馈非常多的，其实就是材料力学里面的拉伸+弯曲组合。比如再沸器支架，挂在塔器顶部，那么我们进行应力评定的时候，就不能只考虑压力作用下的评定，还是要考虑没有压力作用下的评定，很有可能是在没有压力作用下的更危险。每台设备都有他的隐蔽的地方需要我们去发掘，去排除，保证计算的可靠，保证设备的安全。
